Apparatus for selectively controlling the transmission and receiving of wireless messages



Aug. 13, 1929. STARR 1,724,227 APPARATUS FOR 'SELECTIVELY CONTROLLING THE TRANSMISSION AND RECEIVINGOF WIRELESS MESSAGES Filed March 21, 1925 S sheetswsheet 1 Inventor:

Aug. 13, 1929. A; R STARR 1,724,227 APPARATUS FOR SELEGTIVELY CONTROLLING 1:112: TRANSMISSION AND RECEIVING OF WIRELESS MESSAGES Filed March 21, 1925 3 Sheets-Sheet 2 @L A W I o- FPO o m N 3- --c o R N Fo x o o N a as 5: (Q 0 E o m 1/ L q R Inventor.

A fiwfaw Aug. 13, 1929. STARR 1, AlPARATUS FOR SELECTIVELY CONTROLLING THE TRANSMISSION AND RECEIVING 0F WIRELESS MESSAGES v Filed March 21. 1925 3 Sheets-Sheet 3 CJO CDC) .CJQ QCD Inventor:

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Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

ALFRED R. STARR, OF TORONTO, ONTARIO, CANADA.

APPARATUS FOR SELECTIVELY CONTROLLING THE TRANSMISSION AND RECEIVING OE WIRELESS MESSAGES.

Application filed March 21, 1925. Serial No. 17,327.

The principal objectof the .invention is, to enable the transmitting and receiving of messages selectively so that messages may be l'n-oadcastcd to be. effective only in respect to certain selected receiving stations.

The principal features of the invention consist in providing an apparatus adapted to transmit continuous or undamped waves of differentwave lengths successively for definite periods of time and to provide a a receiving apparatus operating in synchronism with the transmitter and adapted to receive the impulses sent.

Further important features of the invention consist in thenovel construction and arrangement of the detectors and amplifiers and in the synchronizing mechanisms whereby the impulses are communicated to a relay apparatus.

In the drawings Figure 1 is a diagram of a. sending apparatus constructed in accordance with this invention.

Figure 2'is a diagram of the receiving apparatus.

Figure 3 is an elevational diagram of the synchronizing mechanism.

In carrying this invention into effect the transmitter is constructed with a plurality of devices termed oscillators or transmitting stations for producing what are known as continuous or undamped waves and each producing Wave lengths of difi'erent frequency. The oscillators are electrically connecte ith a distributor in the form of a commutatorhaving a plurality of insulated sections. These sections are electrically connected successively-preferably in groups of, three, that is to say, if the oscillators are called A, B, and C the segments will be arranged in successive groups A, B, C- A, B, C, etc., in circumferential arrangement, each of the said segments being connected res ectively with the oscillators A, B and C.

rran ed upon the distributor and adjacent to the segments A, B and C are segments 1, 2, 3, 4, each of a length corresponding with each group of segments A B C and the segments 1, 2, 3 and 4 are connected to suitable switches 5, 6, 7 and 8 respectively which connect the circuits into a commonlead =9 connectedcwith the aerial 10.

A rotatable contact member 11 is mounted in axial relation to the circumferentially arranged contact sections and extends between the inner and outer set of contacts; The

from each oscillator will be conveyed from that particular contact 1, 2, 3 or 4 to the aerial.

\Vhen key 1 is depressed the rotating contact .11 in passinglover contact A causes transn'iitter A to emit a wave of say 200 meters wave length for a period of one second. This period of one second is chosen arbitrarily for purposes of illustration and might -be any other period within certain limits.

When the rotating contact passes to the contact B the transmitter B emits a wave of say 550 meters. Similarly when the rotating contact engages the contact C the transmitter C emits a wave of say 940 meters.

A pair of interrupters 12 and 13 preferably operated by the motor drive for the distributor contact 11 are arranged in the lead 9 to the aerial 10. The interrupter l2 operates to cause interruptions at a frequency of 200 per second and the interrupter 13 effects interruptions at a frequency of 10,000 per second.

The oscillators A, B and C are operating continuously as also is the moving distributor contact 11, consequently when one of the switches is closed and the contact 11 moves into contact with the common contact 1, 2,

ting waves from' the respective oscillators successively for definite periods of time.

The'receiving apparatus is provided with an arrangement of tuning coils X, Y, Z corres nding with the oscillators A, B and C 7 an these tuning coils are electrically connected with the segments X Y and Z respectively of a distributor which is synchronized with the distributor in the transmitting mechanism. This synchronized receiver is constructed practically the same as thetransmitter previously described and agy impulses coming into the segments X an Z are picked up by the rotating contact tubes 20 and 21. An audio frequency circuit- 22- is interposed between the amplifiers 20 and 21 and the transformer of thisrir-' cuit separating the amplifiers-is'so designed that it will in combination with the condenserscontained in such audio frequency circuit respond only to a frequency which is regulated by the high frequency interruptor in the sending circuit-which in the present example has been stated as a frequency of 10,000 per second. I

'.l. he amplifying transformer 23 of the circuit 22 is of special construction, both primary and secondary coils being designed to have a fixed inductance value so that when they are connected in parallel with condensers 24 and 25 respectively they will be tuned to a definite frequency which .in the present example is 10,000 per second.

The transformer will then select signals having a frequency of 10,000 per second while signals of otherfrequencies will be greatly attenuated or stopped altogether.

It will be understood from the above that by the introduction of the audio-frequency circuit 22 between the amplifiers 20 and 21, all signals other than those having a frequency of 10,000 per second will be interrupted or prevented from further passage, consequently only those signals which are intended to be carried to the system will be finally transmitted.

The high frequency interrupter at the transmitter interrupts the outgoing waves at a frequency of 10,000 per second while the above-mentioned selective circuit 22 responds to waves of this frequency and no other, thus greatly increasing the. selective properties of the system.

The plate circuit of the amplifier 21 is connected to a central or common contact 27 of a synchronous commutator 28 which is operated in'unison with the rotating contact 14 of the receiving distributor and the commutator connects through brushes 40 and 41 with the terminals of the coils of a difierential relay 26, the neutral point of which is connected to the common B battery of the amplifiers.

The group segments 15, 16, 17 and 18 are connected respectively to one terminal of the relays 29, 30 31 and 32 the other terminals of which are connected by a common lead 33 to the time limit relay 34 and-the adjacent lead of this relay 34 is connected with the filament circuits of the detector and amplifiers 19, 20 and 21.

The relay 34 is co-ordinated with the transmitting and receiving commutators to insure that the incoming signals be perfectly timed safety obstruction.

and that they shall be of a durationregulated=-by.1the relay which has a definite time limit of operation and which thus'acts as a trated in the diagrammatic elevation Figure 3, as being mounted on the shaft of a motor 38 governed to rotate at a constant speed of. 14.40 R. I. M. and whiclro 'ierates the conact.- arm 14 through a worm gearing 39 producing a speed of 5 R. I. M. in said arm. The'commutatoris provided with insulating, segments arranged each side of a central conductor ring which is in constant contact with the brush 27 as above described. The metallic segments on the commutator are arranged in transverse alternation so that the current of the plate circuit of the amplifier 21 flows first through one end of the coil 26 and then to the other and an oscillating effect is produced in the armature 37, there being approximately 192 interruptions per second.

The synchronous commutator 28 which operates at a constant speed transmits the current impulses from the interrupter 12 alternately through the coils of the relay 26 by reason of the staggered relation of the live segments of the commutator 28 contacting alternately with the brushes 40 and 4:1, with the result that the current is directed respectively through the coils of the differential. relay 26, effecting the oscillation of the member 27 at a speed of approximately 8 times per second.

In the event of impulses of a normal high frequency such as ordinary radio telegraph signals, coming from an outside source, entering into the circuit, such foreign impulses will not affect the armature as it is designed torespond to a slow frequency such as mentioned.

The advantage of this feature isthat signals differing very greatly from the chosen freq uency of 200 per second will, due to the inertia of the contact arm of the relay cause it to remain stationary or at most vibrate within narrow limits. but the only frequencies which would operate the relay would be those of 200 or those. differing very slightly from this frequency.

A compensation circuit is connected in'the plate circuitof the amplifier 21. Its purpose is to neutralize the space current which would otherwise flow in the relay coils during the periods whenno signals are being 42, a p tentiometer 43 and a battery 44. One

current in the relay coil will be exactly' neutralized. On the receipt of a signal the value of the plate current will be reduced, current from the compensation battery will then flow in the relay coil and operate it.

In the operation of this apparatus the oscillations of the coils A, B, C, which are of (littering wave lengths, are conducted to the segments A B C and as the contact member 11 rotates the segments A B. C are connected in succession with their overlapping segments 1, 2, 3 and 4 and when either of the segments 1, 2, 3 or 4 is connected by means of its corresponding switch 5, 6, 7 or 8 with the aerial 10 the oscillations from A, B and will be transmitted. The transmitted oscillations are interrupted first by the interrupter l2 producing interruptions of say 200 per second and then interruptions of say 10,000 per second are imparted by the interrupter 13.

These oscillations received by the coils X Y Z of the receiving apparatus which are tuned to the frequency of the coils A B and C respectively, Figure 2, are conducted to the segments X Y Z and the rotating contact 14 connects these segments successively with the overlapping segments 15, 16, 17 and 18.

The coils X Y Z are connected by the common lead D to the detector 19 and amplifiers 20 and 21 but these will only respond to waves having interruptions of a frequenc'y of 10,000 per second. This arrangement effectively eliminates oscillations of other frequencies.

The oscillations transmitted through the amplifiers are conducted to the common lead 27 of the commutator 28 which distributes the oscillations first to one side then the other of the sensitive difl'erential relay coils 26. The oscillating armature is only affected by oscillations of a frequency interruption of 200 to close the circuit to either 0 the fixed contacts 35 or 36, other frequencies circuit of the corresponding relay 29, 30, 31 or- 32 to complete the receiving of the message.

Relays 29, 30, 31, 32 are of the delayed action type. The contactsare closed practically instantaneously when energized and remain closed for a period of twelve seconds. thus bridging over the time between successive impulses originating from the same key 5, 6. 7 or 8 at the transmitter.

The effect of this arrangement is that when a key 5, 6, 7 or 8 is depressed at the transn'iitter, the corresponding relay-29, 30, 31 or 32 will be operated and will stay closed as long as, the key is held closed.

From this description it will be understood that the principal elements in my system of control are found in the production and transmission of a succession of waves of differing lengths produced in regular rotation and in providing a receiving apparatus synchronized with the transmitting apparatus to receive such different. wave lengths.

\Vhat I claim as my invention is 1. A selective control for transmitting and receiving wireless messages, comprising means for transmitting waves of different wave lengths successively for definite periods of time, means for creating a constant high frequency interruption in the transmittedsignals, means operating in synchronism with said transmitting means adapted to receive,

the impulses sent, and a time limit relay in terposed in said receiving means having a limit of time operation coinciding with the transmitting time periods and adapted to operate and pass on only signals of a corresponding time duration.

2. In a selective control for transmitting and receiving wireless messages, the combination with means for transmitting waves of diflerent wave lengths successively for definite periods of time, means operating in synchronism with said transmitting mean.- adapted to receive the impulses sent, of a time limit relay adapted to operate only by signals of a definite period of duration, .a synchronous commutator operating in unison with the receiving member having const-antcontact with said receiver, and a differential relay in the receiver circuit having contacts co-operating with the segments of said commutator.

3. A selective control for transmitting and receiving wireless messages, comprising the combination with a plurality of oscillators producing wave lengths of diflerent frequencies, means for transmitting waves so produced in. regulated intervals, means operating in synchronism with said transmitter adapted to receive the defined. impulses sent, means for producing high frequency interruptions in said waves, a timed. audio-circuit harmonizing with said interruptions,-a sensitive relay in said receivingcircuit, and a synchronous commutator operating in harmony with the receiver and directing the said picleup and a commutator synchronixed with the pick-up means and directing the current alternately through the separate coils of the relay.

5. A selective control for transmitting and receiving wireless messages, comprising the combination with oscillators adapted to produce wave lengths of different frequencies,- of a commutator having a plurality of groups of minor segments, one segment of each group being connected to a corresponding oscillator, major segments coinciding with each of said groups, a synchronized motor, a contact arm operated by said synchronized motor to travel over said commutator and to connect the minor with the major segments, a receiving commutator similar to the aforesaid commutator having a contact arm operated by a motor synchronized with the aforesaid motor, a sensitive differential relay connected with the latter contact arm and adapted to interrupt messages foreign to the oscillations distributed through the first mentioned commutator, a

combination with means for transmitting v waves of different wave lengths successively for definite periods of time, of means for interrupting the waves transmitted at a predetermined frequency, receiving. means operating in synchronism .with said transmitting means, a commutator having constant contact with said receiving means and alternately arranged segments, a sensitive differential relay having its opposing coils connected with the interrupting segments of the latter commutator, a time limit relay connected with said sensitive differential relay, and means for expressing the messages transmitted and received.

7. A selective control for transmitting and receiving wireless messages, comprising the combination with means for transmitting -waves of different wave lengths successively for definite periods of time, of switch means for controlling the distribution of said waves, receiving means operating in synchronism with said transmitting means, relays connected with the receiving means to operate selectively according to the switches operated, a time limit relay connected in multiple with the aforesaid relays, a sensitive differential relay connected with the time limit relay, a definitely timed frequency pick up commutator arranged between the differential relay and the receiving means, and a definitely timed frequency interrupter arranged in the transmitting means.

ALFRED R. STARR.- 

